Field of Invention
The present invention relates to a backpack, and more particularly to a backpack with a suspension arrangement, which suspends the load at the backpack to minimize a continuous bounding movement/force of the backpack to the wearer's body when the wearers walks or runs.
Description of Related Arts
Backpacks generally comprises a bag body and two shoulder straps extended from the bag body, wherein the backpacks rely on the shoulder straps to carry the load at the bag body, the load exerts a backward pulling force at the shoulders of the wearer, causing back fatigue and strain. Especially, students, i.e. the wearers, often carry heavy books to and from school. Therefore, musculoskeletal experts are warning the parents that a young child often has an epidemic of back problems due to the continuous use of heavy backpack. According to the American Occupational Therapy Association, a student backpack should not weight more than 15 percent of the wearer's weight. When the wearer stands still, the loading force at the bag body is a static force equal to the weight of the load. However, when the wearer walks or runs, the loading force at the bag body is larger than the weight of the load. In particular, the loading force will change at all times during the body movement of the wearer. It is because the bag body will move up and down during the body movement of the wearer, wherein a gravity force is added into the weight of the load. In other words, the rapid or vigorous body movement of the wearer will dramatically increase the loading force at the bag body. For the wearers who need to carry heavy load, such as students, campers, hikers, or golfers, the loading force may not be evenly transferred to the shoulder straps. In other words, the center of mass of the wearer will shift during the body movement of the wearer, causing the wearer to trip or fail.
An improved backpack incorporates with a suspended loading device to minimize the up and down movement of the bag body. Accordingly, the suspended loading device comprises a suspension frame, wherein the shoulder straps are coupled at one side of the suspension frame and the bag body is movably coupled at another side of the suspension frame. Due to the relative movement between the bag body and the suspension frame, the up and down movement of the bag body can be minimized to transfer to the shoulder straps. However, such suspended loading device has several drawbacks. Accordingly, the suspension frame is relatively heavy added onto the weight of the bag body. Therefore, the overall weight of the backpack, including the load at the bag body and weight of the suspension frame, will directly exert to the wearer's body through the shoulder straps. In addition, more than one item is disposed in the bag body, which causes the uneven distribution of the weight of the bag body. However, the suspended loading device can only minimize the up and down movement of the bag body but cannot evenly distribute the loading force to the shoulder straps. As a result, the wearer's body will lean toward one side where the heavier load is exerted at one of the shoulder straps.